1. Field of the Invention
This invention relates to coating compositions, and more particularly modified liquid silicate coating compositions, that are useful in treating metals for the preservation thereof. Still more particularly, this invention relates to silicate coating compositions for metal protection wherein said compositions are easy to handle and apply.
2. Discussion of the Prior Art
There are a host of prior art references which teach coating of metal elements, especially metal elements to buried within cementitious material, in order to attempt the preservation thereof. Metals such as reinforcing rods are representative of this latter application. Most of these references require alternative procedures such as heating and the like in order to improve the adhesion of the protective coating. Some require the application of a zinc coating, analogous to anodizing, for example, to achieve the requisite results. All of these procedures are expensive, toxic and require additional investment.
In assignee's co-pending application, U.S. Ser. No. 07/306,796, filed Feb. 6, 1989, there is disclosed a solution and process for coating metal parts comprising a two part solution. One part is made from an aqueous solution of an alkali metal silicate, trisodium phosphate, and at least one compound selected from the group consisting of copper sulfate and powdered zinc. The second part is an aqueous solution of acetic acid. These parts are mixed thoroughly and then can be applied, at a temperature above 40.degree. F., to metal in order to achieve protection. Although this solution will provide some protection for metal used in, for example, cementitious material, there is still a pressing need to provide even more protection to prevent the metal from corrosion and degradation. Additionally, this solution is fairly unstable when mixed and the two parts must be kept separated until just prior to using since pre-mixed material will begin to cure to early.
There is also a pressing need to preserve and protect metals that are placed in storage, for example. Here, pieces of metal that are to be used later, for whatever reason, are kept out in the open or stored in a warehouse for this future use. These metals tend to rust and deteriorate during this storage period.